As is known, tailless airplanes have been devised in the past, typical examples being shown in U.S. Pat. Nos. 3,397,526, 2,539,357 and 2,559,823. Certain prior art tailless aircraft employ a split aileron feature near the wing tips to produce the required yawing moments by increasing the drag on the appropriate side of the aircraft. Such a concept, however, has the dual disadvantage of adding drag and being effective only for wings with relatively high aspect ratios.
U.S. Pat. No. 2,433,649 discloses a rudderless aircraft employing wing tip-mounted spoilers or flaps on a common pivot which produce a yawing moment by adding drag. The aerodynamic drag of such spoilers or flaps, however, is high and the deployed shape can present a highly visible target to some types of detectors. The aforesaid U.S. Pat. No. 2,559,823 discloses a tailless aircraft utilizing paired vanes which pivot about an axis normal to the wing surface to provide a smooth control response. One disadvantage of such vanes, however, is that they are always extended with a rather large total periphery.